<s>
VSI	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
is	O
the	O
latest	O
name	O
for	O
a	O
dialect	O
of	O
the	O
BASIC	O
programming	O
language	O
created	O
by	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
and	O
now	O
owned	O
by	O
VMS	B-Operating_System
Software	O
Incorporated	O
(	O
VSI	O
)	O
.	O
</s>
<s>
It	O
was	O
originally	O
developed	O
as	O
BASIC-PLUS	B-Language
in	O
the	O
1970s	O
for	O
the	O
RSTS-11	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
on	O
the	O
PDP-11	B-Device
minicomputer	B-Architecture
.	O
</s>
<s>
It	O
was	O
later	O
ported	O
to	O
OpenVMS	B-Operating_System
,	O
first	O
on	O
VAX	B-Device
,	O
then	O
Alpha	B-Device
,	O
and	O
most	O
recently	O
Integrity	B-General_Concept
.	O
</s>
<s>
Past	O
names	O
for	O
the	O
product	O
include	O
:	O
BASIC-PLUS	B-Language
,	O
Basic	B-Language
Plus	I-Language
2	O
(	O
BP2	O
or	O
BASIC-Plus-2	O
)	O
,	O
VAX	B-Language
BASIC	I-Language
,	O
DEC	B-Language
BASIC	I-Language
,	O
Compaq	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
and	O
HP	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
.	O
</s>
<s>
Multiple	O
variations	O
of	O
the	O
titles	O
noting	O
the	O
hardware	B-Device
platform	I-Device
(	O
VAX	B-Device
,	O
AlphaServer	O
,	O
etc	O
.	O
)	O
</s>
<s>
VSI	O
BASIC	O
has	O
many	O
FORTRAN-like	O
extensions	O
,	O
as	O
well	O
as	O
supporting	O
the	O
original	O
Dartmouth	B-Language
BASIC	I-Language
matrix	B-Data_Structure
operators	O
.	O
</s>
<s>
Line	B-Application
numbers	I-Application
are	O
optional	O
,	O
unless	O
the	O
"	O
ERL	O
"	O
function	O
is	O
present	O
.	O
</s>
<s>
It	O
allows	O
you	O
to	O
write	O
"	O
WHEN	O
ERROR	O
"	O
error	B-General_Concept
handlers	I-General_Concept
around	O
protected	O
statements	O
.	O
</s>
<s>
One	O
of	O
VSI	O
BASIC	O
's	O
more	O
noteworthy	O
features	O
is	O
built-in	O
support	O
for	O
OpenVMS	B-Operating_System
's	O
powerful	O
Record	B-Application
Management	I-Application
Services	I-Application
(	O
RMS	B-Application
)	O
.	O
</s>
<s>
Before	O
the	O
release	O
VAX	B-Language
BASIC	I-Language
,	O
native	O
RMS	B-Application
support	O
was	O
only	O
available	O
in	O
DEC	O
's	O
COBOL	B-Application
compiler	B-Language
.	O
</s>
<s>
The	O
VSI	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
product	O
history	O
spans	O
a	O
period	O
of	O
more	O
than	O
30	O
years	O
,	O
and	O
it	O
has	O
gone	O
through	O
many	O
name	O
and	O
ownership	O
changes	O
in	O
that	O
time	O
.	O
</s>
<s>
It	O
has	O
also	O
been	O
ported	O
to	O
a	O
succession	O
of	O
new	O
platforms	B-Device
as	O
they	O
were	O
developed	O
by	O
DEC	O
,	O
Compaq	O
,	O
HP	O
and	O
VSI	O
.	O
</s>
<s>
VSI	O
BASIC	O
began	O
as	O
BASIC-PLUS	B-Language
,	O
created	O
by	O
DEC	O
for	O
their	O
RSTS-11	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
and	O
PDP-11	B-Device
minicomputer	B-Architecture
.	O
</s>
<s>
Programming	O
language	O
statements	O
could	O
either	O
be	O
typed	O
into	O
the	O
command	O
interpreter	B-Application
directly	O
,	O
or	O
entered	O
into	O
a	O
text	B-Application
editor	I-Application
,	O
saved	O
to	O
a	O
file	O
,	O
and	O
then	O
loaded	O
into	O
the	O
command	O
interpreter	B-Application
from	O
the	O
file	O
.	O
</s>
<s>
It	O
could	O
be	O
"	O
compiled	B-Language
"	O
into	O
a	O
non-editable	O
binary	O
file	O
,	O
using	O
the	O
"	O
COMPILE	B-Language
"	O
command	O
.	O
</s>
<s>
This	O
command	O
did	O
not	O
produce	O
true	O
machine	B-Language
language	I-Language
programs	O
,	O
but	O
rather	O
a	O
byte	O
code	O
called	O
"	O
tokens	O
"	O
.	O
</s>
<s>
The	O
tokens	O
were	O
interpreted	O
upon	O
execution	O
,	O
in	O
a	O
manner	O
similar	O
to	O
the	O
more	O
modern	O
Java	B-Language
.	O
</s>
<s>
Programs	O
were	O
entered	O
into	O
the	O
command	O
interpreter	B-Application
starting	O
with	O
line	B-Application
numbers	I-Application
,	O
integers	O
from	O
1	O
to	O
32767	O
.	O
</s>
<s>
For	O
ease	O
of	O
external	O
editing	O
of	O
the	O
source	O
file	O
,	O
later	O
versions	O
of	O
BASIC-PLUS	B-Language
also	O
allowed	O
the	O
&	O
character	O
as	O
a	O
line-continuation	O
character	O
.	O
</s>
<s>
For	O
PDP-11	B-Device
systems	O
with	O
virtual	O
memory	O
(	O
RSTS/E	B-Operating_System
)	O
,	O
address	O
space	O
was	O
limited	O
to	O
about	O
64	O
KB	O
.	O
</s>
<s>
With	O
BASIC-PLUS	B-Language
,	O
about	O
half	O
of	O
this	O
was	O
used	O
by	O
the	O
combined	O
command	O
interpreter	B-Application
and	O
run-time	O
library	O
.	O
</s>
<s>
Older	O
RSTS-11	B-Operating_System
systems	O
lacked	O
virtual	O
memory	O
,	O
so	O
the	O
user	O
program	O
had	O
to	O
fit	O
into	O
whatever	O
was	O
left	O
of	O
physical	O
memory	O
after	O
RSTS	B-Operating_System
and	O
BASIC-PLUS	B-Language
took	O
up	O
their	O
share	O
.	O
</s>
<s>
For	O
example	O
,	O
on	O
a	O
PDP-11/35	O
with	O
32K	O
of	O
physical	O
memory	O
,	O
running	O
RSTS-11	B-Operating_System
V04B-17	O
,	O
user	O
programs	O
were	O
limited	O
to	O
7	O
KB	O
.	O
</s>
<s>
Large	O
programs	O
could	O
be	O
broken	O
up	O
into	O
various	O
pieces	O
by	O
use	O
of	O
the	O
"	O
CHAIN	B-Operating_System
"	O
instruction	O
.	O
</s>
<s>
Programs	O
could	O
chain	B-Operating_System
to	O
specific	O
line	B-Application
numbers	I-Application
in	O
a	O
secondary	O
program	O
.	O
</s>
<s>
The	O
use	O
of	O
a	O
shared	O
memory	O
section	O
called	O
core	B-Operating_System
common	I-Operating_System
also	O
allowed	O
programs	O
to	O
pass	O
data	O
among	O
each	O
other	O
as	O
needed	O
;	O
disk	B-Device
files	O
could	O
also	O
be	O
used	O
but	O
were	O
slower	O
.	O
</s>
<s>
The	O
interpreter	B-Application
included	O
a	O
garbage	O
collecting	O
memory	O
manager	O
,	O
used	O
for	O
both	O
string	O
data	O
and	O
byte-code	O
.	O
</s>
<s>
Many	O
of	O
the	O
control	O
structures	O
used	O
in	O
other	O
high-level	O
languages	O
existed	O
in	O
BASIC-PLUS	B-Language
,	O
including	O
WHILE	O
and	O
UNTIL	O
.	O
</s>
<s>
Basic	B-Language
Plus	I-Language
2	O
(	O
BP2	O
or	O
BASIC-Plus-2	O
)	O
was	O
later	O
developed	O
by	O
DEC	O
to	O
add	O
additional	O
features	O
and	O
increase	O
performance	O
.	O
</s>
<s>
It	O
used	O
true	O
compilation	B-Language
into	O
threaded	B-Application
code	I-Application
,	O
and	O
wrote	O
its	O
output	O
to	O
machine	B-Language
language	I-Language
object	B-Application
files	I-Application
.	O
</s>
<s>
These	O
were	O
compatible	O
with	O
other	O
object	B-Application
files	I-Application
on	O
the	O
system	O
,	O
and	O
could	O
be	O
assembled	O
into	O
libraries	O
.	O
</s>
<s>
A	O
linker	B-Application
(	O
the	O
TKB	O
taskbuilder	O
)	O
then	O
created	O
executable	B-Application
files	I-Application
from	O
them	O
.	O
</s>
<s>
BP2	O
programs	O
ran	O
under	O
RSX-11	B-Application
or	O
RSTS/E	B-Operating_System
'	O
s	O
RSX	O
Run	O
Time	O
System	O
.	O
</s>
<s>
These	O
two	O
factors	O
allowed	O
individual	O
BP2	O
programs	O
to	O
be	O
much	O
larger	O
than	O
BASIC-PLUS	B-Language
programs	O
,	O
often	O
eliminating	O
the	O
need	O
for	O
CHAINing	O
.	O
</s>
<s>
Unlike	O
BASIC-PLUS	B-Language
(	O
which	O
was	O
only	O
available	O
on	O
RSTS-11	B-Operating_System
)	O
,	O
BP2	O
allowed	O
use	O
on	O
the	O
RSX-11	B-Application
operating	B-General_Concept
system	I-General_Concept
as	O
well	O
.	O
</s>
<s>
With	O
the	O
creation	O
of	O
the	O
VAX	B-Device
minicomputer	B-Architecture
,	O
DEC	O
ported	O
BASIC-PLUS-2	O
to	O
the	O
new	O
VMS	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
and	O
called	O
it	O
VAX	B-Language
BASIC	I-Language
.	O
</s>
<s>
VAX	B-Language
BASIC	I-Language
used	O
the	O
standard	O
VMS	B-Operating_System
calling	O
standards	O
,	O
so	O
object	O
code	O
produced	O
by	O
VAX	B-Language
BASIC	I-Language
could	O
be	O
linked	O
with	O
object	O
code	O
produced	O
by	O
any	O
of	O
the	O
other	O
VMS	B-Operating_System
languages	O
.	O
</s>
<s>
Source	O
code	O
for	O
BASIC	B-Language
Plus	I-Language
2	O
would	O
usually	O
run	O
without	O
major	O
changes	O
on	O
VAX	B-Language
BASIC	I-Language
.	O
</s>
<s>
When	O
DEC	O
created	O
their	O
Alpha	B-Device
microprocessor	B-Architecture
,	O
VMS	B-Operating_System
was	O
ported	O
to	O
it	O
and	O
renamed	O
OpenVMS	B-Operating_System
.	O
</s>
<s>
VAX	B-Language
BASIC	I-Language
was	O
likewise	O
ported	O
to	O
Alpha	B-Device
and	O
renamed	O
DEC	B-Language
BASIC	I-Language
.	O
</s>
<s>
The	O
BASIC	O
interpreter	B-Application
was	O
permanently	O
dropped	O
at	O
this	O
point	O
,	O
which	O
meant	O
that	O
DEC	B-Language
BASIC	I-Language
programs	O
could	O
only	O
be	O
run	O
as	O
OpenVMS	B-Operating_System
executables	B-Application
,	O
produced	O
by	O
a	O
compile	B-Language
followed	O
by	O
a	O
link	B-Application
.	O
</s>
<s>
When	O
DEC	O
was	O
purchased	O
by	O
Compaq	O
in	O
1997/98	O
,	O
the	O
products	O
were	O
renamed	O
Compaq	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
VAX	B-Device
and	O
Compaq	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
Alpha	B-Device
.	O
</s>
<s>
Likewise	O
,	O
when	O
Compaq	O
merged	O
with	O
HP	O
in	O
2001/02	O
,	O
the	O
products	O
were	O
renamed	O
HP	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
on	O
VAX	B-Device
and	O
HP	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
on	O
AlphaServer	O
.	O
</s>
<s>
HP	O
later	O
released	O
HP	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
on	O
Integrity	B-General_Concept
for	O
their	O
Integrity	B-General_Concept
server	B-Application
platforms	B-Device
based	O
upon	O
Intel	O
's	O
Itanium	B-General_Concept
processors	O
.	O
</s>
<s>
In	O
mid	O
2014	O
,	O
HP	O
sold	O
the	O
whole	O
OpenVMS	B-Operating_System
ecosystem	O
to	O
VSI	O
who	O
renamed	O
the	O
product	O
VSI	B-Language
BASIC	I-Language
for	I-Language
OpenVMS	I-Language
.	O
</s>
<s>
VSI	O
BASIC	O
is	O
a	O
structured	O
variant	O
of	O
BASIC	O
in	O
which	O
line	B-Application
numbers	I-Application
are	O
optional	O
,	O
and	O
the	O
language	O
supports	O
both	O
SUBs	O
and	O
FUNCTIONs	O
.	O
</s>
